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EP0863440A2 - Appareil d'exposition par projection et méthode de fabrication d'un dispositif - Google Patents

Appareil d'exposition par projection et méthode de fabrication d'un dispositif Download PDF

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Publication number
EP0863440A2
EP0863440A2 EP98301443A EP98301443A EP0863440A2 EP 0863440 A2 EP0863440 A2 EP 0863440A2 EP 98301443 A EP98301443 A EP 98301443A EP 98301443 A EP98301443 A EP 98301443A EP 0863440 A2 EP0863440 A2 EP 0863440A2
Authority
EP
European Patent Office
Prior art keywords
diffractive optical
optical system
optical element
projection
light
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP98301443A
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German (de)
English (en)
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EP0863440A3 (fr
EP0863440B1 (fr
Inventor
Yoshiyuki Sekine
Ryusho Hirose
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Canon Inc
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Canon Inc
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Filing date
Publication date
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Publication of EP0863440A3 publication Critical patent/EP0863440A3/fr
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70216—Mask projection systems
    • G03F7/70308—Optical correction elements, filters or phase plates for manipulating imaging light, e.g. intensity, wavelength, polarisation, phase or image shift
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/0025—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for optical correction, e.g. distorsion, aberration
    • G02B27/0037—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for optical correction, e.g. distorsion, aberration with diffracting elements
    • G02B27/0043—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for optical correction, e.g. distorsion, aberration with diffracting elements in projection exposure systems, e.g. microlithographic systems
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
    • G02B27/4205—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant
    • G02B27/4211—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant correcting chromatic aberrations
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
    • G02B27/4205—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant
    • G02B27/4222—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant in projection exposure systems, e.g. photolithographic systems
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
    • G02B27/4272—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having plural diffractive elements positioned sequentially along the optical path
    • G02B27/4277—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having plural diffractive elements positioned sequentially along the optical path being separated by an air space
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/20—Exposure; Apparatus therefor
    • G03F7/2002—Exposure; Apparatus therefor with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70216—Mask projection systems
    • G03F7/70241—Optical aspects of refractive lens systems, i.e. comprising only refractive elements

Definitions

  • This invention relates to a projection exposure apparatus and a device manufacturing method.
  • the invention is suitably usable in manufacture of devices with patterns of a size of submicron or quartermicron order or smaller, such as ICs, LSIs, CCDs or liquid crystal panels, for example, based on a projection optical system with a diffractive optical element for projecting and printing a device pattern of a reticle or mask (hereinafter "mask") on different regions on a wafer through a step-and-repeat procedure or step-and-scan procedure.
  • mask a diffractive optical element for projecting and printing a device pattern of a reticle or mask
  • a projection optical system includes one or more diffractive optical elements mainly for correction of axial chromatic aberration or magnification chromatic aberration.
  • phase type diffractive optical element In respect to efficiency of use of light, use of a phase type diffractive optical element may be preferable.
  • a phase type diffractive optical element if its kinoform is defined idealistically, it shows a diffraction efficiency of 100%.
  • a binary optics element as compared therewith, since its kinoform is defined by approximation with steps, it does not show a diffraction efficiency of 100% even though the element is formed idealistically. With a structure of eight steps, for example, a highest diffraction efficiency will be about 95%.
  • diffraction light unwanted diffraction light
  • Such unwanted diffraction light is not correctly imaged at a desired position, and it produces flare light which reaches the image plane and deteriorates the image quality.
  • a diffractive optical element produces unwanted diffraction light such as described above
  • the unwanted diffraction light which is reflected by the lens barrel can be reduced in its intensity to a level that can be disregarded, by means of barrel design or anti-reflection treatment to the inside wall of the barrel; whereas the unwanted diffraction light that directly passes through the effective diameter of the optical system may cause non-uniform exposure.
  • both of (i) the intensity of unwanted diffraction light relative to the diffraction light of design order or orders (the intensity of regular diffraction light to be used for the imaging), upon the image plane, as well as (ii) the intensity distribution of the unwanted diffraction light upon the image plane, should be considered.
  • the intensity of unwanted diffraction light upon the image plane is nearly equal to zero.
  • to accomplish it is very difficult.
  • a projection exposure apparatus comprising: an illumination optical system for illuminating a mask with light from a light source; and a projection optical system having a diffractive optical element, for projecting an image of a pattern of the mask, as illuminated, on to a substrate, wherein said diffractive optical element is adapted to produce first diffraction light of first order to be used for formation of the image and second diffraction light of second order different from the first order, to be projected on the substrate to provide there a substantially uniform intensity distribution.
  • a projection exposure apparatus comprising: an illumination optical system for illuminating a mask with light from a light source; and a projection optical system having a diffractive optical element, for projecting an image of a pattern of the mask, as illuminated, on to a substrate, wherein said diffractive optical element is adapted to produce first diffraction light of first order to be used for formation of the image and second diffraction light of second order different from the first order, and wherein a portion of the second diffraction light is not to be projected on the substrate and the other portion of the second diffraction light is to be projected on the substrate to provide there a substantially uniform intensity distribution.
  • a projection exposure apparatus for projecting a pattern of a first object on to a second object through a projection optical system, having a feature that said projection optical system comprises first and second diffractive optical elements disposed at or adjacent to the position of an aperture stop, and an aspherical surface lens.
  • said first and second diffractive optical elements are disposed on the opposite sides of the aperture stop.
  • said first and second diffractive optical elements are disposed on a side of the aperture stop facing the first object.
  • said first and second diffractive optical elements are disposed on a side of the aperture stop facing the second object.
  • said first and second diffractive optical elements are set so that unwanted diffraction light not contributable to the imaging is projected on the second object with uniform light intensity distribution.
  • said first and second diffractive optical elements are effective to correct axial chromatic aberration and color comma aberration of said projection optical system.
  • said first and second diffractive optical elements have a relative ratio, not greater than 2.5, of frequencies fR 1 and fR 2 their diffraction gratings at the largest effective diameter.
  • a projection exposure apparatus for projecting a pattern of a first object on to a second object through a projection optical system, having a feature of first and second diffractive optical elements disposed on the opposite sides of an aperture stop, respectively.
  • said first and second diffractive optical elements are set so that unwanted diffraction light not contributable to the imaging is projected on the second object with uniform light intensity distribution.
  • said first and second diffractive optical elements are effective to correct axial chromatic aberration and color comma aberration of said projection optical system.
  • said first and second diffractive optical elements have a relative ratio, not greater than 2.5, of frequencies fR 1 and fR 2 their diffraction gratings at the largest effective diameter.
  • a device manufacturing method comprising the steps of: projecting a pattern of a reticle on to a wafer by use of a projection exposure apparatus according to any one of the first to fifth aspects of the present invention as described above; and performing, after the pattern projection, a development process to the wafer.
  • an optical designing method for an optical system having a diffractive optical element and other optical elements such as lenses comprising: a first step for determining the position of the diffractive optical element with respect to an optical path so that, within a predetermined range on an imaging plane defined by the optical system, predetermined diffraction light of a predetermined order from the diffractive optical element and being contributable to the imaging and unwanted diffraction light not contributable to the imaging have a substantially constant ratio; and a second step for determining optical constants (such as curvature radius, for example) of the diffractive optical element and lenses in accordance with the determination at the first step.
  • a method of producing an imaging optical system for use in a lithographic process, having a diffractive optical element, a refractive optical element and/or a reflective optical element, having a feature that: in optical designing, the position of the diffractive optical element is determined so that, as compared with a different position, an undesirable effect, to an image plane, of diffraction light (unwanted diffraction light) from the diffractive optical element of an order other than a design order is reduced, and then optical constants such as curvature radius, for example, of the diffractive optical element, the refractive optical element and/or the reflective optical element are determined.
  • the undesirable effect includes non-uniformness of light quantity.
  • the position of the diffractive optical element, reducing the undesirable effect is set at or adjacent to an aperture stop.
  • the imaging optical system includes two or more diffractive optical elements.
  • At least one of the refractive optical element and the reflective optical element has an aspherical surface.
  • an imaging optical system which is produced in accordance with the imaging optical system producing method as recited above.
  • a device manufacturing method including a process for imaging and transferring a device pattern on to a substrate by use of an imaging optical system as recited above.
  • a projection exposure apparatus comprising: a projection optical system including an imaging optical system as recited in above; and an illumination optical system for illuminating a mask having a pattern to be projected by said projection optical system.
  • Figure 1 is a schematic view of a main portion of a projection optical system according to a first embodiment of the present invention.
  • Figure 2 shows spherical aberration, astigmatism and distortion of the projection optical system of the first embodiment of the present invention.
  • Figure 3 shows lateral aberration of the projection optical system of the first embodiment of the present invention.
  • Figure 4 shows intensity distribution of unwanted diffraction light as defined on an image plane by the projection optical system of the first embodiment of the present invention.
  • Figure 5 is a schematic view of a main portion of a projection optical system according to a second embodiment of the present invention.
  • Figure 6 shows spherical aberration, astigmatism and distortion of the projection optical system of the second embodiment of the present invention.
  • Figure 7 shows lateral aberration of the projection optical system of the second embodiment of the present invention.
  • Figure 8 shows intensity distribution of unwanted diffraction light as defined on an image plane by the projection optical system of the second embodiment of the present invention.
  • Figure 9 is a schematic view of a main portion of a projection optical system according to a third embodiment of the present invention.
  • Figure 10 shows spherical aberration, astigmatism and distortion of the projection optical system of the third embodiment of the present invention.
  • Figure 11 shows lateral aberration of the projection optical system of the third embodiment of the present invention.
  • Figure 12 shows intensity distribution of unwanted diffraction light as defined on an image plane by the projection optical system of the third embodiment of the present invention.
  • Figure 13 is a schematic view of a main portion of a projection optical system to be compared with the present invention.
  • Figure 14 shows aberrations of a projection optical system to be compared with the present invention.
  • Figure 15 shows lateral aberration of a projection optical system to be compared with the present invention.
  • Figure 16 shows intensity distribution of unwanted diffraction light as defined on an image plane by a projection optical system to be compared with the present invention.
  • Figure 17 is a schematic view of a main portion of another projection optical system to be compared with the present invention.
  • Figure 18 shows aberrations of a projection optical system to be compared with the present invention.
  • Figure 19 shows lateral aberration of a projection optical system to be compared with the present invention.
  • Figure 20 shows intensity distribution of unwanted diffraction light as defined on an image plane by a projection optical system to be compared with the present invention.
  • Figure 21 is a graph for explaining the relation between effective radius and frequency of a diffractive optical element in the first embodiment of the present invention.
  • Figure 22 is a graph for explaining the relation between effective radius and frequency of a diffractive optical element in the second embodiment of the present invention.
  • Figure 23 is a graph for explaining the relation between effective radius and frequency of a diffractive optical element in the third embodiment of the present invention.
  • Figure 24 is a graph for explaining the relation between effective radius and frequency of a diffractive optical element in a projection optical system to be compared with the present invention.
  • Figure 25 is a graph for explaining the relation between effective radius and frequency of a diffractive optical element in another projection optical system to be compared with the present invention.
  • Figure 26 is a schematic view for explaining unwanted diffraction light.
  • Figure 27 is a flow chart for explaining the procedure of optical designing method and optical system producing method, according to the present invention.
  • Figure 28 is a flow chart of a device manufacturing method according to the present invention.
  • Figure 29 is a flow chart of a wafer process according to the present invention.
  • Figure 1 is a schematic view of a main portion of a projection exposure apparatus according to a first embodiment of the present invention.
  • the invention is applied to a projection exposure of step-and-repeat type or step-and-scan type for lithographic process of submicron or quartermicron order or less. This is also the case with other embodiments to be described later.
  • Denoted in the drawing at PL is a projection optical system.
  • the illustration shows a state in which a first object such as a reticle or mask M (hereinafter "mask”) having an electronic circuit pattern formed thereon is illuminated with exposure light from an illumination device ED, comprising a light source and an illumination optical system, and in which the device pattern of the first object M is projected by the projection optical system PL on a shot region of a second object such as a wafer W (silicon substrate), in a reduced scale.
  • the light source may comprise a KrF excimer laser, ArF excimer laser or F 2 laser, for example.
  • a stop which determines the pupil plane of the projection optical system PL.
  • BOE1 and BOE2 are first and second diffractive optical elements formed on the surfaces of lenses, respectively. Each diffractive optical element comprises a binary optics element. These diffractive optical elements BOE1 and BOE2 are provided on the corresponding lenses so that they are placed adjacent to the pupil plane SP and that they sandwich the pupil plane therebetween.
  • This embodiment employs such structure that the first and second diffractive optical elements BOE1 and BOE2 each having a predetermined diffraction grating structure are disposed adjacent to and before and after the pupil plane of the projection optical system PL.
  • This enables superior correction of aberrations including chromatic aberration. Additionally, adverse effect (e.g., non-uniform exposure) on the image plane (shot region) due to the flare component resulting from unwanted diffraction light to be provided by the provision of the diffractive optical elements, can be reduced or avoided.
  • Figure 26 illustrates unwanted diffraction light produced by one diffractive optical element BOE.
  • the unwanted diffraction light comprises diffraction light of a diffraction order or orders different from the order or orders of predetermined diffraction light which is to be used for formation of an image of the pattern of the first object M.
  • a portion of the unwanted diffraction light is not projected on the substrate W, but is incident on the inside wall of the lens barrel and is absorbed thereby.
  • the remaining portion of the unwanted light impinges on the substrate W.
  • the structure in order to avoid non-uniformness of exposure, the structure is arranged to assure that the unwanted diffraction light impinging on the substrate W provides substantially uniform light intensity distribution within the shot region on the substrate.
  • Each of the first and second diffractive optical elements BOE1 and BOE2 is made of a material of quartz.
  • the projection optical system PL comprises lenses of a single glass material of quartz or fluorite, or glass materials of quartz and fluorite. Specifically, in the embodiments described below, all of the diffractive optical elements and lenses may be provided by a single glass material of quartz.
  • two diffractive optical elements which satisfy the above-described conditions i.e., equations (1) and (2) or equations (1') and (2')
  • equations (1) and (2) or equations (1') and (2') may be used.
  • only one diffractive optical element which satisfies these conditions or three diffractive optical elements satisfying the conditions may be used.
  • the pattern (device pattern) of the first object M as illuminated with exposure light from the illumination device ED is projected by the projection optical system PL on to the second object (wafer) W.
  • the exposed wafer is processed by a development treatment, and semiconductor devices are produced.
  • the diffractive optical elements BOE1 and BOE2 according to this embodiment will be explained.
  • the projection optical system PL of this embodiment uses phase type diffractive optical elements as the first and second diffractive optical elements BOE1 and BOE2. It is known that, with a phase type diffractive optical element, if it has an idealistically produced kinoform, it can provide 100% diffraction efficiency (the intensity ratio of the light as deflected and transmitted in a desired direction, to the light incident on the diffractive optical element).
  • phase of light impinging on the diffractive optical element is changed by an amount corresponding to the applied phase function, by which deflection toward a desired direction is accomplished.
  • phase function can be defined as a function of position upon the diffractive optical element.
  • phase function is a function of distance r from the optical axis.
  • phase function ⁇ (r) represents the phase
  • opl(r) optical path length function
  • the optical path length opl(r) necessitates dividing the phase function ⁇ (r) by 2 ⁇ .
  • the shape F(r) above represents the surface shape of a refractive optical element.
  • a diffractive optical element uses a phenomenon that the phase term of light corresponds to a period 2 ⁇ .
  • an aberration-free lens based on a diffractive optical element can be provided by applying the surface shape to the diffractive optical element on the basis of a function as dividing by (n-1) the optical path length function opl(r) where the value range is [0, 1].
  • a diffractive optical element whose diffraction effect is provided by the surface shape of the element i.e., surface protrusions and grooves
  • surface relief type a diffractive optical element whose diffraction effect is provided by the surface shape of the element.
  • a desired aspherical surface effect can be provided by the manner of applying the phase function ⁇ (r)
  • the value range of the optical path length function opl(r) is [0, 1]
  • the depth of necessary surface shape F(r) is of an order of wavelength.
  • the diffractive optical element can be made thin.
  • deflection of light through diffraction by a diffractive optical element becomes larger with longer wavelength, it provides opposite color dispersion characteristic to a refractive optical element of ordinary glass material.
  • correction of chromatic aberration can be done without use of different glass materials.
  • the diffractive optical elements BOE1 and BOE2 of the first embodiment of Figure 1 may be based on these features, as desired.
  • the features as described above are applied to a projection optical system of semiconductor device manufacturing projection exposure apparatus of step-and-repeat or step-and-scan type.
  • the glass material which has sufficient transmissivity to light of such ultraviolet region is limited to SiO 2 and CaF 2 only. Particularly, the glass material for a projection optical system usable with light of F 2 laser is CaF 2 only.
  • the problems of chromatic aberration and increased total thickness of lenses in a projection optical system to be used with exposure light of ultraviolet region can be solved by providing a diffractive optical element of appropriate shape at the position of or adjacent to the pupil position of the projection optical system.
  • a diffractive optical element of appropriate shape at the position of or adjacent to the pupil position of the projection optical system.
  • a diffractive optical element usable in this embodiment may be produced, not by directly forming an idealistic shape (blazed shape or kinoform shape) on a transparent substrate, but by approximating such idealistic shape with stepped shape (with levels).
  • a stepper may be used for production of a diffractive optical element to be used. This facilitates manufacture of a diffractive optical element of fine structure.
  • a diffractive optical element used in this embodiment has a shape approximating the idealistic shape with level structure, the diffraction efficiency does not reach 100% and there is small unwanted diffraction light produced.
  • ⁇ N m [ ⁇ sin( ⁇ m/N)sin( ⁇ (1-m)) ⁇ / ⁇ m sin( ⁇ (1-m)/N) ⁇ ] -2
  • N may be set to about 8 to 16.
  • N may be set to about 8.
  • the procedure when it is applied to designing an optical system having a diffractive optical element and lenses, the procedure includes as shown in Figure 27 (i) a first step for determining the position of the diffractive optical element with respect to an optical path so that, within a predetermined range on an imaging plane defined by the optical system, predetermined diffraction light of a predetermined order from the diffractive optical element and being contributable to the imaging and unwanted diffraction light not contributable to the imaging have a substantially constant ratio, and (ii) a second step for determining optical constants such as curvature and thickness, for example, of the diffractive optical element and lenses in accordance with the determination at the first step.
  • the position of the diffractive optical element is determined so that, as compared with a different position, an undesirable effect, to an image plane, of diffraction light from the diffractive optical element of an order other than a design order is reduced, and then optical constants such as curvature and thickness, for example, of the diffractive optical element, the refractive optical element and/or the reflective optical element are determined.
  • the refractive optical element and/or the reflective optical element may have an aspherical surface, and the undesirable effect may be non-uniformness of exposure.
  • the position with less undesirable effect may be the position at or adjacent to the aperture stop, and the diffractive optical element may be disposed there.
  • At least two diffractive optical elements may be disposed adjacent to the aperture stop within the projection optical system, by which superior aberration correction is assured and undesirable effect of unwanted diffraction light is prevented.
  • the two diffractive optical elements may be disposed so as to satisfy the two conditions of equations (1) and (2) described above. This reduces non-uniformness of exposure, and assures good optical performance.
  • the condition of equation (1) is to geometrically restrict the distance d between the pupil (aperture stop) and the first or second diffractive optical element.
  • the condition of equation (2) is to restrict extension of largest light ray, determining the numerical aperture (NA), from the object point, with respect to the surface of the first or second diffractive optical element.
  • At least two diffractive optical elements are provided within the projection optical system, and they are disposed adjacent to the pupil plane (i.e. aperture stop SP) of the projection optical system.
  • the pupil plane i.e. aperture stop SP
  • unwanted diffraction light is added, upon the image plane, to the regular image (mask pattern image) as background light having substantially uniform light intensity distribution. While the contrast of the image may reduce slightly, substantially uniform contrast is provided over the whole image plane and, therefore, it can be met by a process to be done later.
  • optical path length function opl(r) is used to describe the characteristic of diffractive optical element (binary optics element).
  • opl(r) (C 1 r 2 +C 2 r 4 +C 3 r 6 )/ ⁇ p is used and, based on this, the coefficients C 1 , C 2 and C 3 as well as the wavelength ⁇ are given.
  • the wavelength ⁇ p is one called production wavelength. In designing, it may be the same as or different from the wavelength to be actually used in the optical system. In this embodiment, the exposure light used may have a bandwidth not greater than several hundred picometers (300 pm).
  • z(r) [cr2/ ⁇ 1+ 1- 1+K c 2 r 2 ⁇ ] +Ar 4 +Br 6 +Cr 8 +Dr 10 +Er 12 +Fr 14 and by giving K, c, A, B, C, D, E and F, wherein c is the curvature radius.
  • Figures 2 and 3 illustrate aberrations of Numerical Example 1.
  • Figure 4 shows an intensity distribution of unwanted diffraction light upon the image plane, in this embodiment, wherein the intensity of unwanted light is illustrated as being standardized with respect to the intensity of diffraction light of design order.
  • Calculation of unwanted diffraction light here is based on that there is a circular opening of a radius 50 mm on the object plane and the luminance distribution and light orientation distribution are uniform over the whole circular opening, and that each of two diffractive optical elements has a step structure of eight levels. It is seen from Figure 4 that in this embodiment the intensity ratio of the unwanted diffraction light to the diffraction light of design order is about 0.1% and it is substantially uniform over the whole image plane, and that the effect of the unwanted diffraction light is very small.
  • Figure 21 shows the relation between the effective radius of the diffractive optical element and the frequency, in this embodiment.
  • Figure 5 is a schematic view of a main portion of an optical system according to a second embodiment of the present invention. This embodiment differs from the first embodiment of Figure 1 in the point that diffractive optical elements BOE1 and BOE2 are provided on the surfaces of two lenses which are disposed on one side of the aperture stop SP, facing the image plane. The remaining portion has essentially the same structure.
  • Both of the diffractive optical elements used in this embodiment are disposed in the neighbourhood of the pupil and on the image plane side thereof.
  • Figures 6 and 7 show aberrations of a numerical example (Numerical Example 2) according to this embodiment, to be described below. Although the optical system is provided by a single glass material, aberrations including chromatic aberration are well corrected.
  • Figure 8 shows an intensity distribution of unwanted diffraction light upon the image plane, in this embodiment, wherein the intensity of unwanted light is illustrated as being standardized with respect to the intensity of diffraction light of design order. Calculation of unwanted diffraction light here is based on that there is a circular opening of a radius 50 mm on the object plane and the luminance distribution and light orientation distribution are uniform over the whole circular opening, and that each of two diffractive optical elements has a step structure of eight levels.
  • the intensity ratio of the unwanted diffraction light to the diffraction light of design order is about 0.11% and it is substantially uniform over the whole image plane, and that the effect of the unwanted diffraction light is very small.
  • Figure 22 shows the relation between the effective radius of the diffractive optical element and the frequency, in this embodiment.
  • Figure 9 is a schematic view of a main portion of an optical system according to a third embodiment of the present invention. This embodiment differs from the first embodiment of Figure 1 in that diffractive optical elements BOE1 and BOE2 are provided on the surfaces of lenses which are disposed on the object side of the aperture stop SP. The remaining portion has essentially the same structure.
  • Figures 10 and 11 show aberrations of a numerical example (Numerical Example 3) according to this embodiment, to be described below.
  • the optical system is provided by a single glass material, aberrations including chromatic aberration are well corrected.
  • Figure 12 shows an intensity distribution of unwanted diffraction light upon the image plane, in this embodiment, wherein the intensity of unwanted light is illustrated as being standardized with respect to the intensity of diffraction light of design order.
  • Calculation of unwanted diffraction light here is based on that there is a circular opening of a radius 50 mm on the object plane and the luminance distribution and light orientation distribution are uniform over the whole circular opening, and that each of two diffractive optical elements has a step structure of eight levels.
  • the intensity ratio of the unwanted diffraction light to the diffraction light of design order is about 0.13% and it is substantially uniform over the whole image plane, and that the effect of the unwanted diffraction light is very small.
  • Figure 23 shows the relation between the effective radius of the diffractive optical element and the frequency, in this embodiment.
  • Figure 13 is a schematic view of an optical system which is to be compared for reference with the projection optical systems according to the numerical examples 1 - 3 above.
  • diffractive optical elements BOE1 and BOE2 are provided on the surface of one lens, which is on the object side of the aperture stop SP and is far remote from it, and on the surface of another lens which is on the image plane side of the aperture stop SP and is adjacent to it.
  • Figures 14 and 15 show aberrations of the reference example of projection optical system shown in Figure 13. It is seen that, although the optical system is provided by a single glass material, aberrations including chromatic aberration are well corrected.
  • Figure 16 shows an intensity distribution of unwanted diffraction light upon the image plane, in this reference example, wherein the intensity of unwanted light is illustrated as being standardized with respect to the intensity of diffraction light of design order.
  • Calculation of unwanted diffraction light here is based on that there is a circular opening of a radius 50 mm on the object plane and the luminance distribution and light orientation distribution are uniform over the whole circular opening, and that each of two diffractive optical elements has a step structure of eight levels.
  • the intensity ratio of the unwanted diffraction light to the diffraction light of design order is about 3.2% at the center of the picture field, and that, regarding the uniformness of intensity ratio on the image plane, there is a difference of about 1% between the central portion and the peripheral portion.
  • Such intensity ratio and its uniformness are insufficient for a projection exposure apparatus for submicron or quartermicron order lithography.
  • Figure 24 shows the relation between the effective radius of the diffractive optical element and the frequency, in the case where the projection optical system shown in Figure 13 is used. Numerical data of the reference example where the projection optical system of Figure 13 is used, will be described below.
  • Figure 17 is a schematic view of another optical system which is to be compared for reference with the projection optical systems according to the numerical examples 1 - 3 described above.
  • diffractive optical elements BOE1 and BOE2 are provided on the surface of one lens, which is on the object side of the aperture stop SP and is adjacent to, and on the surface of another lens which is on the image plane side of the aperture stop SP and is far remote from it.
  • Figures 18 and 19 show aberrations of the reference example of projection optical system shown in Figure 17. It is seen that, although the optical system is provided by a single glass material, aberrations including chromatic aberration are well corrected.
  • Figure 20 shows an intensity distribution of unwanted diffraction light upon the image plane, in this reference example, wherein the intensity of unwanted light is illustrated as being standardized with respect to the intensity of diffraction light of design order.
  • Calculation of unwanted diffraction light here is based on that there is a circular opening of a radius 50 mm on the object plane and the luminance distribution and light orientation distribution are uniform over the whole circular opening, and that each of two diffractive optical elements has a step structure of eight levels.
  • the intensity ratio of the unwanted diffraction light to the diffraction light of design order is about 3% at the center of the picture field, and that, regarding the uniformness of intensity ratio on the image plane, there is a difference of more than about 1.2% between the central portion and the peripheral portion.
  • Such intensity ratio and its uniformness are insufficient for a projection exposure apparatus for submicron or quartermicron order lithography.
  • Figure 25 shows the relation between the effective radius of the diffractive optical element and the frequency, in the case where the projection optical system shown in Figure 17 is used.
  • Numerical data of the reference example where the projection optical system of Figure 17 is used, will be described below.
  • Figure 28 is a flow chart of procedure for manufacture of microdevices such as semiconductor chips (e.g. ICs or LSIs), liquid crystal panels, or CCDs, for example.
  • semiconductor chips e.g. ICs or LSIs
  • liquid crystal panels e.g. LCDs
  • CCDs complementary metal-oxide-semiconductors
  • Step 1 is a design process for designing a circuit of a semiconductor device.
  • Step 2 is a process for making a mask on the basis of the circuit pattern design.
  • Step 3 is a process for preparing a wafer by using a material such as silicon.
  • Step 4 is a wafer process which is called a pre-process wherein, by using the so prepared mask and wafer, circuits are practically formed on the wafer through lithography.
  • Step 5 subsequent to this is an assembling step which is called a post-process wherein the wafer having been processed by step 4 is formed into semiconductor chips. This step includes assembling (dicing and bonding) process and packaging (chip sealing) process.
  • Step 6 is an inspection step wherein operation check, durability check and so on for the semiconductor devices provided by step 5, are carried out. With these processes, semiconductor devices are completed and they are shipped (step 7).
  • Step 29 is a flow chart showing details of the wafer process.
  • Step 11 is an oxidation process for oxidizing the surface of a wafer.
  • Step 12 is a CVD process for forming an insulating film on the wafer surface.
  • Step 13 is an electrode forming process for forming electrodes upon the wafer by vapor deposition.
  • Step 14 is an ion implanting process for implanting ions to the wafer.
  • Step 15 is a resist process for applying a resist (photosensitive material) to the wafer.
  • Step 16 is an exposure process for printing, by exposure, the circuit pattern of the mask on the wafer through the exposure apparatus described above.
  • Step 17 is a developing process for developing the exposed wafer.
  • Step 18 is an etching process for removing portions other than the developed resist image.
  • Step 19 is a resist separation process for separating the resist material remaining on the wafer after being subjected to the etching process. By repeating these processes, circuit patterns are superposedly formed on the wafer.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
  • Lenses (AREA)
  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
  • Diffracting Gratings Or Hologram Optical Elements (AREA)
EP98301443A 1997-02-28 1998-02-27 Appareil d'exposition par projection et méthode de fabrication d'un dispositif Expired - Lifetime EP0863440B1 (fr)

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JP6223997 1997-02-28
JP6223997 1997-02-28
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JP10044563A JP3065017B2 (ja) 1997-02-28 1998-02-10 投影露光装置及びデバイスの製造方法
JP44563/98 1998-02-10
JP4456398 1998-02-10

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EP1075150A2 (fr) * 1999-07-31 2001-02-07 Lg Electronics Inc. Système de lentilles de projection
US6538821B2 (en) 1997-09-22 2003-03-25 Nikon Corporation Projection optical system
US6600606B2 (en) 2000-03-15 2003-07-29 Canon Kabushiki Kaisha Projection optical system with diffractive optical element
US6606144B1 (en) 1999-09-29 2003-08-12 Nikon Corporation Projection exposure methods and apparatus, and projection optical systems
US6674513B2 (en) 1999-09-29 2004-01-06 Nikon Corporation Projection exposure methods and apparatus, and projection optical systems
CN103399390A (zh) * 2013-05-10 2013-11-20 无锡国盛生物工程有限公司 生物芯片扫描仪荧光收集物镜

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KR101248328B1 (ko) * 2004-06-04 2013-04-01 칼 짜이스 에스엠티 게엠베하 강도 변동이 보상된 투사 시스템 및 이를 위한 보상 요소
JP4646575B2 (ja) * 2004-08-31 2011-03-09 キヤノン株式会社 半導体装置の製造方法
DE102008054737A1 (de) 2008-01-10 2009-07-16 Carl Zeiss Smt Ag Mikrolithographische Projektionsbelichtungsanlage sowie Objektiv hierfür
CN110568727B (zh) * 2018-06-05 2021-07-02 上海微电子装备（集团）股份有限公司 一种曝光系统、曝光方法和光刻机

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US6538821B2 (en) 1997-09-22 2003-03-25 Nikon Corporation Projection optical system
US6781766B2 (en) 1997-09-22 2004-08-24 Nikon Corporation Projection optical system
EP1075150A2 (fr) * 1999-07-31 2001-02-07 Lg Electronics Inc. Système de lentilles de projection
EP1075150A3 (fr) * 1999-07-31 2005-04-27 Lg Electronics Inc. Système de lentilles de projection
US6606144B1 (en) 1999-09-29 2003-08-12 Nikon Corporation Projection exposure methods and apparatus, and projection optical systems
US6674513B2 (en) 1999-09-29 2004-01-06 Nikon Corporation Projection exposure methods and apparatus, and projection optical systems
US6864961B2 (en) 1999-09-29 2005-03-08 Nikon Corporation Projection exposure methods and apparatus, and projection optical systems
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US6600606B2 (en) 2000-03-15 2003-07-29 Canon Kabushiki Kaisha Projection optical system with diffractive optical element
CN103399390A (zh) * 2013-05-10 2013-11-20 无锡国盛生物工程有限公司 生物芯片扫描仪荧光收集物镜
CN103399390B (zh) * 2013-05-10 2015-12-02 无锡国盛生物工程有限公司 生物芯片扫描仪荧光收集物镜

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US6266192B1 (en) 2001-07-24
JP3065017B2 (ja) 2000-07-12
EP0863440A3 (fr) 1999-07-07
DE69813658D1 (de) 2003-05-28
JPH10303127A (ja) 1998-11-13
DE69813658T2 (de) 2003-12-18
EP0863440B1 (fr) 2003-04-23

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